This invention relates to hearing aids, and particularly to in-canal hearing aids including means for minimizing entry into the hearing aids of wax-fluid-like substances present within the ear canal; such means also facilitating solvent washing away any such substances adhering to the hearing aids.
A major problem in the use of small hearing aids for full insertion within the ear canal of a user is the clogging of and even permanent damage to the hearing aid caused by penetration of foreign substances into the hearing aid (by xe2x80x9cforeign substancesxe2x80x9d being meant substances foreign to the hearing aid itself). Primarily, although not limited thereto, such foreign substances are wax-like ear secretions and various fluidsxe2x80x94both oil-like secretions and water entering the ear during washing and the like.
The prior art shows many examples of means for protecting hearing aids from such substances. One typical arrangement is shown in U.S. Pat. No. 4,984,277 to Bisgaard, et al. Therein is shown a typical in-canal hearing aid terminating in a sound port pointing, during use of the hearing aid, directly towards the user""s ear drum. For preventing entry of foreign substances into the sound port, a small cap-like, impervious shield is mounted on the hearing aid directly in front of the sound port but spaced therefrom by mounting legs. Sound exiting from the sound port passes outwardly from the hearing aid through the spaces between the shield mounting legs and, while the sound is thus not directly aimed at the ear drum, the sound is guided by the walls of the ear canal to the ear drum.
As described in the patent, a primary function of the cap-like shield is to prevent foreign substances within the ear canal from being forced directly into the hearing aid during insertion of the hearing aid into the ear canal. In effect, the cap-like shield functions as a plow for pushing aside foreign substances in the path of advance of the hearing aid.
In a number of other patents, such as U.S. Pat. Nos. 3,408,461, 4,532,649, 4,706,778 and 4,972,488, apertured plates or screens are placed in close proximity, and often inside, the hearing aid sound port for trapping and collecting wax which would otherwise migrate into the sound port. A problem in all these patents (including the aforecited Bisgaard et al patent), is that the various openings through the plates or screens (or around the Bisgaard et al cap) are pervious to fluids within the ear canal which can pass through the openings or around the cap directly into the sound port. While collected wax is likely to merely clog the sound exit, fluids entering into the hearing aid receiver are likely to permanently damage the receiver. Also, because of the possibility of entry of fluids into the receiver, the use of wax-dissolving solvents for washing away accumulated wax is generally precluded. Thus, removal of accumulated wax can be quite difficult.
While many other patents show various schemes for collecting or trapping foreign substances as a means for protecting the hearing aids, experience has shown that such collection mechanisms are generally unsatisfactory and, indeed, many presently used hearing aids effectively ignore the problem and leave to the user the need for frequent cleaning or replacement of the hearing aid. The structures disclosed in my co-pending, parent application greatly improve this situation. The structures disclosed herein provide additional solutions to the foreign substance problem.
An in-canal hearing aid includes a receiver having a sound port facing, when in use, directly towards the ear drum. Disposed forwardly of the sound port is a foreign substance shield which provides gravity assisted paths for fluids downwardly past and spaced from the sound port and to the floor of the ear canal below.
In first embodiments, the shields, similar to those disclosed in my copending parent application, are mounted on or comprise extensions of the hearing aid receiver. For simplicity of mounting, the shields can be disposed at the ends of cylindrical boots telescoped onto the receivers.